/*
 * Copyright (C) 2009 M. Hautle.
 * 
 * This file is part of TrackedBean.
 * 
 * TrackedBean is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any later version.
 * 
 * TrackedBean is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License along with TrackedBean. If not, see <http://www.gnu.org/licenses/>.
 */
package ch.trackedbean.copier.engine;

import java.beans.*;
import ch.trackedbean.common.*;
import ch.trackedbean.copier.*;
import ch.trackedbean.util.*;

/**
 * Object holding a deep mapping.
 * 
 * @author M. Hautle
 */
public class DeepMappingHolder extends AbstractSimpleMappingHolder {
	/** Flag indicating if {@link #copySrc2Dst(Object, Object, IMappingContext)} should override an object hold by the destination property. */
	protected final boolean overrideSrc;

	/** Flag indicating if {@link #copyDst2Src(Object, Object, IMappingContext)} should override an object hold by the destination property. */
	protected final boolean overrideDst;

	/** The type evaluator to use for {@link #copyToDestination(Object, Object, IMappingContext)} or null. */
	protected final ITypeEvaluator srcEvaluator;

	/** The type evaluator to use for {@link #copyToSource(Object, Object, IMappingContext)} or null. */
	protected final ITypeEvaluator dstEvaluator;

	/**
	 * Default constructor.
	 * 
	 * @param src The source property
	 * @param dst The destination property (on the object holding the mapping annotations)
	 * @param overrideSrc Flag indicating if {@link #copySrc2Dst(Object, Object, IMappingContext)} should override an object hold by the source property
	 * @param overrideDst Flag indicating if {@link #copyDst2Src(Object, Object, IMappingContext)} should override an object hold by the destination property
	 * @param srcEvaluator The type evaluator to use for {@link #copyToSource(Object, Object, IMappingContext)} or null
	 * @param dstEvaluator The type evaluator to use for {@link #copyToDestination(Object, Object, IMappingContext)} or null
	 * @param readOnly Flag indicating if the mapping should be 'readonly' so that {@link #copyDst2Src(Object, Object, IMappingContext)} will not be executed
	 * @param lazy Flag indicating if the property should be fetched lazy
	 */
	public DeepMappingHolder(PropertyDescriptor src, PropertyDescriptor dst, boolean overrideSrc, boolean overrideDst, ITypeEvaluator srcEvaluator,
			ITypeEvaluator dstEvaluator, boolean readOnly, boolean lazy) {
		super(src, dst, readOnly, lazy);
		this.overrideSrc = overrideDst;
		this.overrideDst = overrideDst;
		this.srcEvaluator = srcEvaluator;
		this.dstEvaluator = dstEvaluator;
	}

	/**
	 * Default constructor.
	 * 
	 * @param el The expression
	 * @param targetType The type of the value reurned by the el expression
	 * @param dst The destination property (on the object holding the mapping annotations)
	 * @param overrideSrc Flag indicating if {@link #copySrc2Dst(Object, Object, IMappingContext)} should override an object hold by the source property
	 * @param overrideDst Flag indicating if {@link #copyDst2Src(Object, Object, IMappingContext)} should override an object hold by the destination property
	 * @param srcEvaluator The type evaluator to use for {@link #copyToSource(Object, Object, IMappingContext)} or null
	 * @param dstEvaluator The type evaluator to use for {@link #copyToDestination(Object, Object, IMappingContext)} or null
	 * @param readOnly Flag indicating if the mapping should be 'readonly' so that {@link #copyDst2Src(Object, Object, IMappingContext)} will not be executed
	 * @param lazy Flag indicating if the property should be fetched lazy
	 */
	public DeepMappingHolder(String el, Class targetType, PropertyDescriptor dst, boolean overrideSrc, boolean overrideDst, ITypeEvaluator srcEvaluator,
			ITypeEvaluator dstEvaluator, boolean readOnly, boolean lazy) {
		super(el, targetType, dst, readOnly, lazy);
		this.overrideSrc = overrideDst;
		this.overrideDst = overrideDst;
		this.srcEvaluator = srcEvaluator;
		this.dstEvaluator = dstEvaluator;
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("unchecked")
	public void copyToDestination(Object src, Object dst, IMappingContext context) {
		try {
			final Object srcValue = srcProp.getValue(src, UNDEFINED);
			// skip if the source value was undefined
			if (srcValue == UNDEFINED)
				return;
			// set the destination to null if the source was null
			if (srcValue == null) {
				dstProp.setValue(dst, null);
				return;
			}
			final Class<?> type = getType(dstProp, srcEvaluator, srcValue);
			// lookup if the object was allready converted
			Object dstValue = context.getElement(srcValue, type);
			if (dstValue == null) {
				// get the destination bean and copy the values (context registration will be done by the mapper call)
				dstValue = getCorrespondingBean(dstProp, type, dst, overrideDst);
				BeanMapperManager.getMapper(dstValue.getClass()).copySrc2Dst(srcValue, dstValue, context);
			}
			dstProp.setValue(dst, dstValue);
		} catch (Exception e) {
			throw new TechnicalException("Error while copying " + this.srcProp.getPath() + " to " + this.dstProp.getPath(), e);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("unchecked")
	public void copyToSource(Object src, Object dst, IMappingContext context) {
		try {
			final Object dstValue = dstProp.getValue(dst, UNDEFINED);
			// do nothing if there's no way to copy the value
			if (dstValue == UNDEFINED)
				return;
			// set the destination to null if the source was null
			if (dstValue == null) {
				srcProp.setValue(src, null);
				return;
			}
			final Class<?> type = getType(srcProp, dstEvaluator, dstValue);
			// lookup if the object was allready converted
			Object srcValue = context.getElement(dstValue, type);
			if (srcValue == null) {
				// get the destination bean and copy the values (context registration will be done by the mapping call)
				srcValue = getCorrespondingBean(srcProp, type, src, overrideSrc);
				BeanMapperManager.getMapper(dstValue.getClass()).copyDst2Src(dstValue, srcValue, context);
			}
			srcProp.setValue(src, srcValue);
		} catch (Exception e) {
			throw new TechnicalException("Error while copying " + this.dstProp.getPath() + " to " + this.srcProp.getPath(), e);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	@SuppressWarnings("unchecked")
	public Object getDstValue(Object dst) {
		final Object dstValue = dstProp.getValue(dst, null);
		if (dstValue == null)
			return null;
		final Object srcValue = create(getType(srcProp, dstEvaluator, dstValue));
		return BeanMapperManager.copyDst2Src(dstValue, srcValue);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	@SuppressWarnings("unchecked")
	public Object getSrcValue(Object src) {
		final Object srcValue = srcProp.getValue(src, null);
		if (srcValue == null)
			return null;
		final Object dstValue = create(getType(dstProp, srcEvaluator, srcValue));
		return BeanMapperManager.copySrc2Dst(srcValue, dstValue);
	}

	/**
	 * Returns an bean instance for the given property.<br>
	 * If the property of the bean allready contains a non <code>null</code> value then simply this value is returned. Otherwise a new bean (of the property
	 * type) will be instanciated.
	 * 
	 * @param acc The accessor
	 * @param type The type to use for the property
	 * @param dstBean The bean which owns the destination property
	 * @param override If an allready existing property value should be overriden
	 * @return A bean instance
	 */
	@SuppressWarnings("unchecked")
	protected Object getCorrespondingBean(IValueAccessor acc, Class type, Object dstBean, boolean override) {
		if (override)
			return create(type);
		final Object dstValue = acc.getValue(dstBean, null);
		if (dstValue != null)
			return dstValue;
		return create(type);
	}

	/**
	 * Creates an instance of the given type.
	 * 
	 * @param <T> The type
	 * @param type The type
	 * @return An instance of the given type
	 */
	protected <T> T create(Class<T> type) {
		try {
			return type.newInstance();
		} catch (Exception e) {
			throw new TechnicalException("Error while creating " + type.getName(), e);
		}
	}

	/**
	 * Returns the type to use for the given accessor.
	 * 
	 * @param acc The accessor for the property
	 * @param evaluator The evaluator for the property
	 * @param src The source value to 'convert'
	 * @return The type to use
	 */
	protected Class<?> getType(IValueAccessor acc, ITypeEvaluator evaluator, Object src) {
		if (evaluator != null)
			return evaluator.getCorrespondingType(src);
		return acc.getType();
	}
}